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Toia GV, Mileto A, Borhani AA, Chen GH, Ren L, Uyeda JW, Marin D. Approaches, advantages, and challenges to photon counting detector and multi-energy CT. Abdom Radiol (NY) 2024; 49:3251-3260. [PMID: 38744702 DOI: 10.1007/s00261-024-04357-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Revised: 04/21/2024] [Accepted: 04/21/2024] [Indexed: 05/16/2024]
Abstract
Photon counting detector CT (PCD-CT) is the newest major development in CT technology and has been commercially available since 2021. It offers major technological advantages over current standard-of-care energy integrating detector CT (EID-CT) including improved spatial resolution, improved iodine contrast to noise ratio, multi-energy imaging, and reduced noise. This article serves as a foundational basis to the technical approaches and concepts of PCD-CT technology with primary emphasis on detector technology in direct comparison to EID-CT. The article also addresses current technological challenges to PCD-CT with particular attention to cross talk and its causes (e.g., Compton scattering, fluorescence, charge sharing, K-escape) as well as pile-up.
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Affiliation(s)
- Giuseppe V Toia
- Departments of Radiology and Medical Physics, University of Wisconsin School of Medicine and Public Health, 600 Highland Ave, Madison, WI, 53792, USA.
| | - Achille Mileto
- Department of Radiology, University of Washington, Seattle, WA, USA
| | - Amir A Borhani
- Department of Radiology, Northwestern University, Chicago, IL, USA
| | - Guang-Hong Chen
- Departments of Radiology and Medical Physics, University of Wisconsin School of Medicine and Public Health, 600 Highland Ave, Madison, WI, 53792, USA
| | - Liqiang Ren
- Department of Radiology, UT Southwestern Medical Center, Dallas, TX, USA
| | - Jennifer W Uyeda
- Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Daniele Marin
- Department of Radiology, Duke University Health System, Durham, NC, USA
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Herweg K, Rutstrom D, Nadig V, Stand L, Melcher CL, Zhuravleva M, Schulz V, Gundacker S. Timing limits of ultrafast cross-luminescence emission in CsZnCl-based crystals for TOF-CT and TOF-PET. EJNMMI Phys 2024; 11:59. [PMID: 38977509 DOI: 10.1186/s40658-024-00663-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 06/27/2024] [Indexed: 07/10/2024] Open
Abstract
BACKGROUND Good timing resolution in medical imaging applications such as TOF-CT or TOF-PET can boost image quality or patient comfort significantly by reducing the influence of background noise. However, the timing resolution of state-of-the-art detectors in CT and PET are limited by their light emission process. Core-valence cross-luminescence is an alternative, but well-known compounds (e.g. BaF2) pose several problems for medical imaging applications, such as their emission wavelength in the deep UV. CsZnCl-based materials show promise to solve this issue, as they provide fast decay times of 1-2 ns and an emission wavelength around 300 nm. RESULTS In this work, we investigated two CsZnCl-compounds: Cs2ZnCl4 and Cs3ZnCl5. We validated the previously published decay times on a time-correlated single-photon counting setup with 1.786 ± 0.016 ns for Cs2ZnCl4 and 1.034 ± 0.013 ns for Cs3ZnCl5. The setup's high resolution enabled the discovery of an additional prompt emission component with a significant abundance of 98 ± 18 (Cs2ZnCl4) and 86 ± 14 (Cs3ZnCl5) photons/MeV energy deposit. In a PET coincidence experiment, we measured the best coincidence time resolution (CTR) of 62 ps (FWHM) for Cs2ZnCL4 coupled to FBK VUV SiPMs with silicon oil. To assess the CTR for lower energies, we filtered the energy along the Compton continuum and found a deteriorated CTR that seems to be mainly influenced by photon statistics. Furthermore, this study gave us a rough estimate of e.g. 150 ps (FWHM) CTR at 100 keV energy for Cs2ZnCL4. From measurements with high activity of 14 MBq to check for pile-up effects we assume that Cs2ZnCl4 is better suited for high-rate time-of-flight applications than lutetium-based oxides. Simulations demonstrated that the stopping power of Cs2ZnCl4 is lower than for LSO:Ce,Ca, meaning that a high amount of material would be needed for TOF-PET applications. However, the stopping power seems acceptable for applications in TOF-CT. CONCLUSIONS The fast decay time, state-of-the-art CTR in benchtop experiments and high-rate suitability make CsZnCl materials a promising candidate for time-of-flight experiments. We consider especially TOF-CT a suitable application due to its relatively low X-ray energies (~ 100 keV) and the thusly acceptable stopping power of Cs2ZnCl4. Currently, further exploration of the prompt emission and its creation mechanism is planned, as well as investigating the light transport of Cs2ZnCl4 in longer crystals.
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Affiliation(s)
- Katrin Herweg
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany.
| | - Daniel Rutstrom
- Scintillation Materials Research Center, University of Tennessee Knoxville, Knoxville, TN, USA
- Department of Materials Science and Engineering, University of Tennessee Knoxville, Knoxville, TN, USA
| | - Vanessa Nadig
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Luis Stand
- Scintillation Materials Research Center, University of Tennessee Knoxville, Knoxville, TN, USA
- Department of Nuclear Engineering, University of Tennessee Knoxville, Knoxville, TN, USA
| | - Charles L Melcher
- Scintillation Materials Research Center, University of Tennessee Knoxville, Knoxville, TN, USA
- Department of Materials Science and Engineering, University of Tennessee Knoxville, Knoxville, TN, USA
- Department of Nuclear Engineering, University of Tennessee Knoxville, Knoxville, TN, USA
| | - Mariya Zhuravleva
- Scintillation Materials Research Center, University of Tennessee Knoxville, Knoxville, TN, USA
- Department of Materials Science and Engineering, University of Tennessee Knoxville, Knoxville, TN, USA
| | - Volkmar Schulz
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
- Hyperion Hybrid Imaging Systems GmbH, Aachen, Germany
- Physics Institute III B, RWTH Aachen University, Aachen, Germany
| | - Stefan Gundacker
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany.
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Yamada A. Quantifying image quality: are we approaching the grail? Eur Radiol 2024; 34:4492-4493. [PMID: 38175224 DOI: 10.1007/s00330-023-10563-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 12/11/2023] [Accepted: 12/18/2023] [Indexed: 01/05/2024]
Affiliation(s)
- Akira Yamada
- Department of Radiology, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Nagano, 390-8621, Japan.
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Sakaida H, Ichikawa Y, Yamazaki A, Sakuma H, Takeuchi K. Ultra-High Spatial Resolution Images of the Temporal Bone Obtained With a Newly Released Photon-Counting Detector Computed Tomography. EAR, NOSE & THROAT JOURNAL 2024:1455613241235551. [PMID: 38656190 DOI: 10.1177/01455613241235551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2024] Open
Affiliation(s)
- Hiroshi Sakaida
- Department of Otorhinolaryngology-Head and Neck Surgery, Mie University Graduate School of Medicine, Tsu, Mie, Japan
| | - Yasutaka Ichikawa
- Department of Radiology, Mie University Graduate School of Medicine, Tsu, Mie, Japan
| | - Akio Yamazaki
- Department of Radiology, Mie University Hospital, Tsu, Mie, Japan
| | - Hajime Sakuma
- Department of Radiology, Mie University Graduate School of Medicine, Tsu, Mie, Japan
| | - Kazuhiko Takeuchi
- Department of Otorhinolaryngology-Head and Neck Surgery, Mie University Graduate School of Medicine, Tsu, Mie, Japan
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